Cellulose-ester composition



Patented June 28, 1927.

UNITED STATES PATENT OFFICE.

GEORGE L SCHWARTZ, 01' WILMINGTON, DELAWARE, ASBIGNOB TO I. I. DU ION! DE NEMOURS & COMPANY, 01 WILMINGTON, DELAWARE, A COBPOBA'I'ION OI DELAWARE.

CELLULOSE-ESTEB COMPOSITION.

Ilo Drawing.

This invention relates to celluloseester to advantage in placeof the castor oil which usually functions as the softener-at'the present time in pyroxlyin coating compositions.

Another jectof my invention is to pro vide a new, odorless artificial'leather.

' The newsofteners, which are preferably 4 mixed g'lycerides of coconut oil acids and acetic acid, are described and claimed in'my copending application, Serial No. 551,734

filed April .11, 1922, Patent No. 1,558,299 of Oct. 20,- 1925. In the present case I claim the combination of these new substances with cellulose esters"(and particularly with nitrocellulose) to form new and Valuable .coating' compositions.

The vegetable oils have long been used as softeners of pyroxlyin, and in particular castor oil and blown rapeseed oil have been used. Both of theseoils are glycerides of unsaturated fatty acids. Their iodine numbers are high, and probably as a result of this unsaturated condition they are subject to certain physical or chemical changes.

For example, castor oil readily becomes rancid when exposed in a pyroxylin film, and it gradually undergoes oxidation which causes a hardening of the film. Practically.

the only low melting vegetable oil that does not have a high iodine numberis coconut oil. This oil is available in large quantities and would be an excellent softener of pyroxylin if its melting point were somewhat lower. It. is much less subject to.

rancidity development and to gradual oxidation than oils-now used, because the per-- centage of unsaturated contains is very low.

I have found that it is often desirable to use as a softener asubstance which has fmild solvent power for pyroxylin. All of glycerides which it i the known vegetable oils are practically Application fled Illne' 15,.1023. Serial racism.

I have .discovered that if an acyl group of a lower fatty acid be introduced into one or more of the glycerides of coconut oil, or of various other vegetable oils, the 'solvent' power 'of the resulting glyceride for proxylin is appreciably increased, while at the same time the freezing point of the lyceride is lowered. This lowering of the r eezing point is sometimes 'quite' marked Commercial coconut oil, for example hasa freezing point of from'14 to 22 (l, -w ereas, after the. introduction of an 'acetyl'group to form a mixed ester, the meltin point is usually between -5 and -13 6., the exact"vah 1e depending upon the extent to which the acetyl group has displaced higher fattyv acid radicals in the glycerides pres- -ent.' In' general a mixed glyceride' -made in accordance with my process should have -a freezingpoint below 10 (1., especially where the mixed glyceride is to be used as a softener of pyroxylin, although in some cases the increase in solvent power attending the introduction of a lower fatty acid radical maybe so great as to render the glyceride suitable as a softener eventhough the freezing point thereof be substantially above 10 C.

The expression lower fatty acid is used herein to mean either formic, acetic, or propionic, acid; and the expression higher fatty. acid has reference to acids of the (l H O series containing. more than nine carbon atoms. The alcohol radical of the mixed ester may be the radical of any one of various polyhydric alcohols, and especially of thelower polyhydric alcohols having between-one and four-hydroxyl groups, the principal members. of this class. being glycerol and ethylene, propylene, andbutylene, glycols.

Where; thenew softener has' been obtained by the action of acetic acid on coconut oil, of which the chief constituent is the glyeride of lauric acid, the newsoftener Wlll consist of a mixture of-mixed esters of which the major part will be aCetyl-laurim'with coconut oil acids, ranging Various alternative methods ofproducing the new softener have been set forth in my above mentioned application, Serial No. 551,734., Patent No. 1,558,299 of Oct. 20, 1925; only my preferred method will be given herein, this method being as follows:

The following ingredients are mixed in a flask that is provided'witha reflux condenser and are heatedfor 1 1 hours in-an oil bath at a temperature where the acet1c acid boils vigorously.

' Partsibiv Glycerine (containing 5% water) 967 Glacial acetic acid (99.5% acid) 2250 Coconut oil acids (mean mol. wt. 208)-- 1560 Sulfuric acid. 0.7

The condenser is then changed to a distilling position and as the acetic acid concentration decreases the temperature of the mixture rises and is held at 160-17 5 C. throughout the remaining heating period. A stream of nitrogen is passed through the mixture throughout this latter heating stage to swee out water as formed. After neutralization is practically complete the crude product is washed with an aqueous sodium chloride solution to remove sulfuric acid. The washed product is then heated for two hours on a steam bath with 2% of its weight of decolorizing carbon and is filtered. The finished product obtained by carrying out this process on a small scale was a light brown, transparent, oily liquid with a slight odor resembling coconut oil and freezing at 10 to -11 C. It contained 1.03% free coconut oil acids. The yield was 87.2% of thetheoretical. The finished product is miscible in all proportions in mineral oil; it.

colloids pyroxylin at normal temperatures; and it does not become rancid.

A mixture of mixed glycerides prepared by the above method is practically non-volatile and cannot be distilled at pressures as low as 14 mm. without partial decomposition'. This product consists of a mixture of all the possible glycerides of acetic acid and from some triacetin through the mixed glycerides to and including some cononut oil. The freezing point varies according to the ratio of acetyl to coconut oil acid groups and usually falls within the range of 5 to ---13 C.

The coconut oil acids that I have used were obtained by hydrolysis, with subsequent distillation under reduced pressure, of commercial coconut oil.

Coconut oil, as has been indicated above, is the oil with which I prefer to start, but other materials may with advantage be converted into acetyl-glycerides in the manner above described, as, for example, commer cial stearic acid, -which contains a large proportion of palmitic acid, or palm kernel oil,

or the acids of this oil.

The new softeners, when obtained from oils such as coconut oil, may be defined generically as mixtures of acetyl derivatives of glycerides of two or more higher fatty acids each having from 10 to 16 carbon atoms. The glyceride mixture prepared in accordance with the above examples will contain a substantial proportion of diacetylglycerides of the higher fatty acids, as, for

example, diacetyl-laurin, diacetyl-myristin,

and diacetyl-palrnitin.- The molecular structure of the alpha-gamma-diacetyl-laurin, which is typical, is probably as follows:

' mo-o-cocn,

H OCO-(CE-I)N'CH3 In addition to the alpha-mono-acetyllaurin whose structure has been shown in .the firstof the above graphical formulas,

Per cent. Capro1c (C H O 0.25 Caprylic (C H O 0.25 Capric (C H O 19.5 Lauric (C H O 40.0 lVIyristic (C H O 24.0 Palmitic (O l-I 0 10.6 Oleic(C H O 5.4

A decidedly greater lowering of the freezing point and increase in solvent power of the higher fatty acid glycerides is attained by introducing two, instead of merely one, acetyl group into the glyceride molecules. My new class of softeners includes broadly both the monoacetyl-di-acyl-glycerides and the diacetyl-mono-acyl-glycerides, where acyl, is used to mean the acid radical of a higher fatty acid, 'as well as corresponding glycerides containing one or two formyl, or

' one'or two propionyl, groups. These new softeners may be designated briefly as mixed. glycerides.

This mixed glyceride is a more effective softener for pyroxylin than is castor oil, as

is indicated by the fact that a film containwith a lubricant such as mineral oil or esters of aliphatic alcohols with the higher fatty saturated acids such as stearic.

The following is a sample coating composition without a lubricant.

The ratio of mixed glyceride or a mixture of thesemixed glycerides and lubricant to pyroxylin in films containing pigment can be varied from pyroxylin 1.00softener 0.75 to pyroxylin 1.00.softener 1.62. In

films containing no pigment the ratios can be varied between pyroxylin 1.00-.so ftener 0.62 to pyroxylin LOO-softener 1.25. High ratios of softener tend to produce films too soft or sticky for good embossing and low ratios tend to roduce stiff material.

As the volatile solvent in the above formulas there may be used a mixture containing benzene 38% and ethyl acetate 62%, or a mixture containing benzene 50%, ethyl acetate 25% and denatured alcohol 25%.

Many solvent mixtures other than these two may of course be used. For example, as the active solvent there may be used either acetone, acetone oils, methylacetone (a commercial mixture containing methyl .acetate, methyl alcohol, and acetone), or an ether-alcohol mixture; and as the diluent there may be used, for example, ethyl alcohol, benzine or benzol.

The ratio of volatile solvent to non-volatile constituents may of course vary widely; thus, instead of the 11 to 3 ratio in the above as the-softener is especially advantageous.

when applied to fabrics in the manufacture of artificial leather (fabrikoid, etc.'). tificial leather containing the new nitrocels lulose composition is freefrom the objectionable odor of castor oil, and is remarkabkyl pliable and durable.

hen working with cellulose acetate the acetyl-laurins should be used in conjunction vlith another solvent softener such as triace m.

Where the coating composition isto be applied by calendering, and is in the form of a plastic mass, the ratio of volatile solvent -to' non-"01atile constituents may be as little as 1 to 3.

Although the mixed -glycerides of higher and lower fatty acids are especially applicable as softeners of nitrocellulose in connection with the manufacture of artificial leather, they are also valuab e softeners or modifiers of nitrocellulose in all of the pyroxylin industries. For example, 'acetyl-laurius can be used as a softener in pyroxylin lacquers and enamels where it has been customary, in the past, to use castor oil. The quality of the lacquers and enamels is much improved by the use of the new softener because it is not subject, to oxidation as is castor oil. Acetyl-laurin may also be used as a camphor substitute in the manufacture of celluloid; it has the advantage over camphor that the product is softer and less liable to discoloration when exposed to sunlight. In fact, in any of the pyroxylin industries, Where a softener or modifier has been used, the new products described will find Valuable application.

I claim:

1. A composition of matter comprising nitrocellulose and a mixed ester of a lower and a higher saturated fatty acid, the alcohol radical of said ester being that of a polyhydric alcohol having between 1 and 4 hydroxyl groups.

2. A composition as set forth in claim 1 in which the mixed ester has a freezing point below 10 C.

A composition of matter comprising a cellulose ester and a-mixed ester of a lower saturated fatty acid and a higher saturated fatty acid having from 10 to 16 carbon .atoms, the alcohol radical of said ester being that'of a polyhydric alcohol having between 1 and 4 hydroxl groups.

lower saturated fatty acid and a higher saturated fatty acid having from 10 to 16 carbon'atoms, the glyceride having a freezing. point below 10 C.

'6. A composition of matter comprising" nitrocellulose and. a mixed glyceride of a lower and a higher saturated fatty acid.

A coating composition comprising 'a' mixture of pyroxylin and a softener consisting of a mlxedglyceride of a lower and a higher saturated fatty acid.

8. A coating composition comprising py'- roxylin and a mixed glyceride of acetic acid and a higher saturated'fatty acid. y

9. A coating composition com rising pyroxylin and a mixed glyceride o acetic acid and a higher saturated fatty acid, said glyceride having a .freezing point below C. v

10. A coating composition comprising pyroxylin anda mixed glycerideof. acetic nod and a higher saturated fatty acid having from 10 to 16 carbon atoms.

11. A coating composition comprising 100 parts.of pyroxylin and from about 62 to 162 parts of a mixed glyceride of a lower and a higher saturated fatty acid.

12. A coating composition comprising 100 parts of pyroxylin and from about 62. to 162 parts of a'mixed glyceride of acetic acid and. of a higher saturated fatty-acid whose molecular structure includes from 10 to 16 carbon atoms, L

13. A coating composition comprising pyroxylin and a softener therefor consistmg, of an acetyl-laurin.

14. Acoating composition comprising 100 parts of pyroxylin and from about 7 5' to 162 parts of a softener containing an acetyllaurin.

15. A coating composition comprising nitrocellulose, a lubricant, and a mixed ester of a lower and a higher fatty acid, the alcohol radical of said ester being that of a polyhye dric alcohol having between 1 and 4 hydroxyl groups.

16. A coating composition comprising nitrocellulose, a lubricant, and a mixed glyceride of a lower and a higherfatty acid.

17. A coating vcomposition comprising nitrocellulose, a lubricant, and a mixed glyceride' of a lower and' a higher fatty acid, said mixed glyceride having a freezing point below 10 C.

18. A coating composition comprising nitrocellulose, a lubricant, and a mixed lyceride of acetic acid and -of a higher gatty acid having from 10 to 16 carbon atoms.

19. A coating composition comprising nitrocellulose, a lubricant, and an acetyl; laurin.

20. A coating composition comprising 100 parts of nitrocellulose, from about 1O to 20 parts of alubricant, and from. about 75 to 162 parts of a mixed glyceride of acetic acid and of a higher fatty acid having-from 10 to 16 carbon atoms. v

21. A composition as set forth in claim 15 in which the lubricant is petrolatum.

22, A composition as set forth in claim 16 in which the lubricant is pe'trolatum.

23. A composition as set forth in claim 17 in which the lubricant ispetrolatum.

24. A textile fabric having on one side a practically odorless pyroxylin com osition containing as a softener a mixed g yceride of a lower and a higher saturated fatty acid, said'composition retaining its flexibility and freedom from odor for a prolonged period.

25. A pyroxylin-coated fabric in which the pyrox lin coating contains as a softener an acetylaurin.

26. A composition as set forth in claim- 18 in which the lubricant is petrolatum."

27-. A composition as set forth in claim 19,.

in which thevlubiicant is petrolatum.

28. A composition as set forth in claim 20 in which the lubricant is petrolatum.

, 29. "A composition asset forth in claim 1 in-which a 'pigmj nt; constitutes one component of the composition.

30. A composition as set forth in claim 4 in which a pigment constitutes one component of the composition.

31. A composition as set forth in claim 8 in which" a. pigment constitutes one component of the composition. 32.. composition as set forth in claim 13 in whichfaf pigment constitutes one com--- ponent of the composition.

33.--A composition as setforth'in claim 15 in whichilapigment constitutes one component of the composition...

34. A' composition as set forth in claim 1 g which also includes a volatile solvent. V

35. composition'as set forth in claim 4 which also includes a volatile solvent.

,36. A composition asset forth in claim 9 which also include's a "blatile solvent.

37. A composition a sj set forth in claim '13 which also includes a'volatile solvent. t 38. A composition ascs'et forth in claim 15 which alsoincludes a volatile solvent.

' 39. A composition as set forth in claim 18 which also includes a ,volatile. solvent.

40. A composition of matter comprising a cellulose ester and a mixed ester of a lower saturated, fatty acid and a highersaturated fatty acid, the alcohol radical of said ester being that of a polyhydric alcohol having between 1 and 4 hydroxyl groups. 41. A composition 0 matter comprisin a celluloseesterfand a mixed-glyceride o a lower saturated fatty acid and a higher saturated fatty acid.

In testimon whereof I afiix m signature.

EORGE L. SCH ARTZ. 

